Overhaul if I have to get VAR cranks.

[markc]

I have made my mind up to get a 337, can someone explain the whole VAR crank issue I have seen batted about, and mentioned in trade-a-plane ads ?

What is the cost differential if say an engine is @ 1450.

Cheers,

Mark

[Ernie Martin]

Because of an AD that some consider faulty if an engine is disassembled and it does not have a VAR crank, then a VAR crank needs to be bought and installed. VAR stands for Vacuum Arc Remelt, a process that supposedly strengthens the metal of a crankshaft. I say "supposedly" because some consider that the data which led to the this AD is suspect, and that non-VAR cranks are just as sound. But it doesn't matter, the regulations require you to replace non-VAR cranks when engines are disassembled and this adds considerably to the cost of an overhaul. Working from memory -- and I could be way off here -- it adds between $1,500 and $3,000.

Ernie

[Dave Underwood]

Just for clarity, although I have not re-read the AD for quite some time, it requires the replacement of a non-VAR crank any time the case is split. This might suggest you can still run on condition Part 91 provided you don't ever split the case. The bottom ends of these engines are pretty good.

If memory serves me correctly, the issue with the non-VAR crank is interstitials or very small voids or irregularities that can form in the traditional casting process. These very small voids become the start points for stress risers and thus crank failures.

There used to be a credit towards a replacement crank if you have that issue, however the last time I looked at the overall economics, the additional price of a factory reman gave you a pretty good warranty and added value to your aircraft. You also got the most up to date engine so that is the route I took.

Mind you that was before the current price of 100LL and softening of aircraft prices.

Regards - Dave

[WebMaster]

Dave is correct, in that if the case is opened, the crank must be a VAR crank before it is closed back up. Two years ago, I replaced one of my engines with a factory Reman. At the same time, I got a heavy case engine. As I recall, at that time, VAR crank was $4,500. When added to the cost of overhaul and repair, it was marginally more expensive to get a factory reman engine.

With the factory reman, you get a warranty. I had to use the warranty, because the seal on the accessory case shaft that drives the hydraulic pump, was faulty. They paid for the complete removal of the engine, the case, provided new parts. I'm not certain about overhaul shops, if they would pay for the same kind of things.

There is the additional advantage of a reman for resale, however with today's prices, I doubt it really affects pricing.

Your engine, at 1450 hours, does not require a rebuild. Jerry has one that is 800 hours past TBO, and still running strong. If there is a problem with the engine, I would suggest getting a firm quote on rebuild, and a price on reman.

[Skymaster337B]

Risk Management! At only 1450 hours I wouldn't overhaul any IO-360 that was running well...maybe a top end if needed. But I understand that the same IO-360 engine in a different airplane (I think a Piper twin) had a recommended overhaul time of 2,000 hours. So why the difference? $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Back to risk management, the Skymaster's unique inline design allows you to accept more of a risk with engine lose. Currently my engines have almost 1,700 hours on them and they are running very well.